The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A typical automatic transmission system has an advantage in terms of starting/transmission because a torque converter acts as a fluid clutch, thereby obtaining a damping effect.
On the other hand, an automated manual transmission (AMT) system and a dual clutch transmission (DCT) system have high fuel efficiency because a clutch is automatically controlled based on a manual transmission mechanism without using a torque converter.
However, the automated manual transmission system directly connects an engine and a clutch in order to thereby improve fuel efficiency and power transmission efficiency, but on the other hand, has no damping factor so that a jolt or clutch slip may occur depending on a torque change. Therefore, it requires an algorithm for predicting the transmission torque characteristics of a dry clutch in real time.
Thus, conventionally, the transmission torque characteristics of a clutch have been predicted using a torque-stroke curve (T-S curve) of a dry clutch. Here, the T-S curve is obtained by converting, into data, the transmission torque characteristics of a dry clutch depending on a stroke of a clutch actuator.
Meanwhile, when a released clutch is engaged, the time at which torque begins to be actually transmitted through the clutch is referred to as a touch point.
However, the T-S curve varies while the vehicle is moving for various reasons such as deterioration and expansion of a disk cushion, thermal deformation of a cover plate, abrasion of disk facings, and variation of the frictional coefficient, and thus, an error may occur in the learning touch point.
Therefore, if a learning value of a clutch touch point is greater than the position of an actual touch point, a clutch actuator stroke greater than the actual touch point is applied, so that an impact due to the clutch engagement may occur when clutch torque is applied.
The description of the technical background above has been made merely for the purpose of helping understanding the background of the present disclosure, and it should not be taken as an admission that the description belongs to the prior art known to those skilled in the art.